AAMOF As A Matter Of Fact
AFAIK As far as I know
ASAP As Soon As Possible - usually used when impatient.
AWGTHTGTTA Are We Going To Have To Go Through This Again?
Alternative form is AWGTHTGTATA (...Through ALL This Again?)
AWHFY Are we having fun yet?
B4 Before
B4N Bye for Now
BAC By Any Chance
BAD Broken as Designed
BBFN Bye Bye For Now
BBL Be Back Later
BBR Burnt Beyond Repair
BBS Bulletin Board System
BCNU Be seein' you! (saying goodbye)
BFN Bye For Now
BION Believe it or not
BIOYIOP Blow It Out Your Input Output Port
BK Because
BMTIPG Brilliant minds think in parallel gutters
BRB Be right back (typically used when leaving briefly during a Conference)
BRS Big Red Switch
BTA But then Again (in response to IOW)
BTAIM Be that as it may
BTOBD Be there or be dead
BTSOOM Beats the S**t Out Of Me
BTW By the way
BWQ Buzz Word Quotient
BYKT But You Knew That
BYKTA But You Knew That Already
CAD Control-Alternate-Delete or Computer Aided Design
CADET Can't add, doesn't even try
CIM CompuServe Information Manager-The program
CIS CompuServe Information System (tm)
CI$ (same as above)
CLM Career Limiting Move
CMIIW Correct Me If I'm Wrong
CO Conference
CP Copy Protection
CRPG Character (or computer) Role Playing Game
CU See you
CUL See You Later
CUL8R See you later
CYA Cover Your A** (Ascii ?)
CYL See You Later
DIIK Darn if I know
DILLIGAFF Do I Look Like I Give a Flying Filament
DL or D/L Download (transmit to you)
DNPM Darn Near P***ed Myself
DOM Dirty Old Man
DTRT Do The Right Thing
DWIMC Do What I Mean, Correctly
DWIMNWIS Do What I Mean, Not What I Say
EOD End Of Discussion
EOL End Of Lecture
EOT End Of Thread
ESAD Eat S...t and Die
ESOSL Endless Snorts of Stupid Laughter
ETLA Extended Three Letter Acronym
FB Files Busy
FCFS First come, first served
FDROTFL Falling Down Rolling On The Floor Laughing
FFRD Flying freep in a rolling donut (I don't give a...)
FISH First In, Still Here
FITB Fill In The Blank....
FOAF Friend of A Friend
FOTCL Falling Off The Chair Laughing
FRED Flaming Ridiculous Electronic Device
FTF Face to Face
FUBAR Fouled up beyond all recognition (also as FOOBAR or as a filename: FOO.BAR
FUD Fear, uncertainty, and doubt
FURTB Full up ready to burst (about hard disk drives!)
FWIW For what it's worth
FYI For your information
gd&h grinning, ducking and hiding
G,D&R Grinning, ducking, and running
G,D&RF Grinning, ducking and running FAST!
G,D&RVVF Grinning, ducking and running VERY VERY FAST
GA Go Ahead
GDW Grin, Duck and Weave
GFR Grim File Reaper (pervasive data destroyer)
GGC Goo Goo Cluster (cause zits & intestinal blockage)
GIGO Garbage in, Garbage Out
GIGO Garbage In, Gospel Out (people accepting blindly what the computer says)
GIWIST Gee I Wish I'd Said That
GLG Goofy Little Grin
GLGH Good Luck and Good Hunting
GMTA Great minds think alike
GOK God Only Knows
GOTFIA Groaning On The Floor In Agony
GOWI Get on with it
GPF General Protection Fault (Old UAE, New Name!)
GP,F Go Puke, Fast!
HSIK How Should I Know (sometime HTFSIK)
HTH Hope this helps
IAAA I am an accountant
IAAL I am a lawyer
IANAA I am not an accountant
IANAL I Am Not A Lawyer
IAC In any case
IAE In any event
IIABDFI If it ain't broke, don't fix it.
IIRC If I Recall Correctly
IITYWYBMAB If I Tell You, Will You Buy Me A Beer
IITYWYBAD If I Tell You, Will You Buy Another Drink
IMO In my opinion
IMAO In My Arrogant Opinion
IMCO In my considered opinion
IMCDO In My Conceited Dogmatic Opinion.
IME In My Experience
IMHO In my humble opinion [the speaker is never humble]
IMNSHO In My Not So Humble Opinion
IMO In My Opinion
IMPOV In my point of view
INAL I'm Not A Lawyer
INPO In No Particular Order
IOW In other words
ITFA In the final analysis
IWBNI If would Be Nice If
IYFEG Insert Your Favourite Ethnic Group
JAM Just a moment
JAS Just a second
JAWS Just another Windows shell
JFYI Just For Your Information
JIC Just In Case
KCBIWIYWI Keep Coming Back, It Works If You Work It
KMA Kiss my arm (shouldn't be used online...)
KISS Keep It Simple Stupid
LABATYD Life's a bitch and then you die
LLTA Lots and Lots of Thunderous (or Thundering) Applause
LMAO Laughing My Arm Off
LOL Laughing Out Loud
LTMSH Laughing 'Til My sides Hurt
MLA Multiple Letter Acronym
MOF Matter Of Fact
MORF Male Or Female
MOTAS Member of the Appropriate Sex
MOTOS Member of the Opposite Sex
MOTSS Member of the Same Sex
MOTM Member of the Month
MOTH Humorous Collectibles Forum variation on Member of the Month
MUNG Mash Until No Good
MYOB Mind Your Own Business
NAVY Never Again Volunteer Yourself
NBD No Big Deal
NBL Not Bloody Likely
NFG No Freeping Good
NFW No Freeping Way
NICBDAT Nothing Is Certain But Death And Taxes
NIMBY Not In My Back Yard
NIMTO Not In My Term of Office
NINO Nothing in, nothing out
NOYB None Of Your Business
NPLU Not People Like Us
NQA No Questions Asked
NQOS Not Quite Our Sort
NRN No Reply Necessary
NTIM Not That It Matters
NTIMM Not That It Matters Much
NUI Network User Identification
OBTW Oh, By the Way
OIC Oh, I see
OTF On the Floor
OTL Out To Lunch
OTOH On the other hand
OTTH On the third hand
OTTOMH Off The Top Of My Head
PABG Packing a Big Gun
PBM Play by Mail (Games)
PDN Public Data Network
PF&HOMW Printed, Framed & Hanging On My Wall
PGY Post Graduate year PGY-1, PGY-2 etc. used in PGY Med.
PITA Pain in the Anatomy
PLOKTA Press Lots of keys to abort
PMBI Pardon my butting in
PMETC Pardon Me Etc.
PMFBI Pardon Me for butting in
PMFJI Pardon me for jumping in
PMJI Pardon my Jumping in
PnP Plug and Pray
POSSLQ Person of Opposite Sex sharing living quarters
POV Point Of View
PPN Programmer Project Number; currently known as UserID
PTB Powers That Be
PTO Patent and Trademark Office (US Govt)
PPPP Previous Paragraph was Polemical Position
RFD Request For Discussion
RHIP Rank Has Its Privileges
RLCO Real Life Conference
RNA Ring, No Answer
ROF,L Rolling on floor, laughing
ROFL <same>
ROFLAHMSL Rolling On Floor Laughing And Holding My Sides Laughing
ROTBA Reality On The Blink Again
ROTFL Rolling On The Floor Laughing
ROFLASTC Rolling On The Floor Laughing And Scaring
ROFLASC <same> The Cat. Originated, I'm told by Pamela Dean, who types with a cat on her lap.
ROTFLMAAOBPO Rolling On The Floor Laughing My A*s And Other Body Parts Off
ROTM Right On The Money
ROY G. BIV An acronym for the colors of the spectrum-Red Orange Yellow Green Blue Indigo Violet
RPG Role Playing Games
RSN Real Soon Now (when application X or other vaporware will arrive)
RTFM Read the "friendly" manual (or message)
SFLA Stupid Four Letter Acronym
SITD Still in the dark
SL Section Leader
SMOP Small Matter of Programming
SNAFU Situation normal, all fouled up
SO Significant Other
SOP Standing Operational Proceedures
SOS Same old Stuff
SSDD Same stuff, different day
SUFID Screwing Up Face In Disgust
SWAG Simple Wild A** Guess
SWMBO She who must be obeyed
SysOp System Operator, person who runs the BBS/Forum
SYT Sweet Young Thing
TAF That's all Folks
TAFN That's all for Now
TANJ There Ain't No Justice
TANSTAAFL There Ain't No Such Thing As A Free Lunch
TBYB Try Before You Buy
TDM Too Dang Many
TFS Three Finger Salute (Ctl-Alt-Del)
TFTT Thanks For The Thought
TGIF Thank God Its Friday
TIA Thanks in advance
TIC Tongue In Cheek
TINALO This Is Not A Legal Opinion
TINAR This Is Not A Recommendation
TIWTGLGG This Is Where The Goofy Little Grin Goes
TJATAW Truth, Justice, And The American Way
TLA Three Letter Acronym (now surpassed by MLA)
TM Thread mangler
TPTB The Powers That Be
TRDMC Tears Running Down My Cheeks
TSJD Texas Size Jelly Donut
TSR Terminate and stay resident program
TSR Totally Stupid Rules
TTBOMK To The Best Of My Knowledge
TTFN Ta Ta For Now
TTL4N That's the lot for now
TTYL Talk to You Later
TYVM Thank You Very Much
UAE Unrecoverable application error (Bane of Windows' users! Now surpassed by GPF)
UL or U/L Upload (send to the BBS)
UNCLE Unified Nuclear Coalition of Latvian Emigrants
WAEF When All Else Fails
WAMKSAM Why Are My Kids (or Kitties) Staring At Me?
WIBAMU Well I'll be a Monkey's Uncle
WIMP Windows, Icons, Mouse, Pointing (to describe Windows and other similar interfaces)
WizOp Wizard SysOp; the primary forum administrator for a forum
WOA Work Of Art
WOFTAM Waste of Flaming time and money
WTF What the Freep
WTFDIK What the Freep Do I Know
WTH What The Heck
WYSIWYG What you see is what you get
WYSBYGI What you see before you get it
WYGIWYPF What you get is what you pay for
WYTYSYDG What You Thought You Saw, You Didn't Get
YADS Yet Another DOS Shell
YAFA Yet Another "Fine" Abbreviation
YAP Yet Another Ploy
YMMV Your Mileage May Vary
ZNT Ziffnet

Actions performed by the writer are often wrapped in smaller-than- "<" and greater-than- ">" signs:

<g> Grinning
<gg> Big grin (etc.)
<BG> Big grin
<eg> Evil grin
<ig> Impish grin
<dg> Devilish grin
<s> Smiling
<ss> Big smile (etc.)
[s] Smiling sarcastically
<g,d&r> Grinning, ducking & running
<sheepish grin>
<silly grin>
<lewd wink>
<raising eyebrows>
<arching eyebrows>
<<mounting the soapbox>>
<<falling off the soapbox>>


some others:

<!> An important part of a message
<?> One part of the message contains a questionable item
<ahem> clearing your throat just before saying something controversial
<sp?> word/name/phrase probably contains a spelling error

Emoticon: n. a figure created with the symbols on a keyboard that is usually read with the head tilted to the left. Used to convey the spirit in which a line of text was typed.

:-) <smile> or <grin>
:) midget Smile
:> Midget Smiley
:-) )-: Masking theatrical comments
:/) Not funny
;-) Wink (or wink and a smile)
;) midget Wink
;> " "
:-))) reeeel happy, big smile
:-> Alternate happy face
:-( Unhappy
:-c Real unhappy
:-C Unbelieving (jaw dropped)
:-< Forlorn
;-C Sardonic incredulity
:-} Crooked Smile
:-i Semi-Smiley
:-7 User after a wry statement
TAF That's All, Folks! That's All, Folks!